THE MIDINFRARED COLOR OF NGC-6946

We analyze the new mid-infrared maps of NGC 6946 for variations in the color ratio of the 7-to-15 mu m emission. Our preliminary findings ar e that this mid-infrared color is remarkably constant between arms and inter-arm regions, and as a function of radius in the disk, excluding the nuclear region. As surface brightness ranges by more than an orde r of magnitude and the radius runs from about 0.5 to 3 kpc, the color ratio remains constant to about +/-20%. Our interpretation is that (1) hard UV radiation from OB stars does not dominate the heating of the grains radiating in the mid-infrared; and (2) that surface brightness variations are driven primarily by surface-filling fraction in the dis k, and by radiation intensity increases in starburst environments, suc h as the nucleus of NGC 6946.